Hump hose installation on MK2

[AndyBC]

As requested in another thread, below are the details of the hump hose installation on my mark 2 for the benefit of those who are looking to do the same in the future

Benefits:
-eliminates risk of damage to muffler inlet fitting by dampening the vibration from the exhaust riser
-reduces vibration to hull and appears to reduce over-all noise (could be placebo affect but I truly believe there is a little less noise)

Difficulty level: easy.  The hardest part was removing the old hose, followed by putting on the new hoses.  Took me 1.5-2 hours altogether.

Tools/equipment:
-Exhaust Hump Hose 1-5/8"I.D X 6" (catalinadirect #Z2152 $52 USD)
-Exhaust Hump Hose 1-5/8"I.D. x 8" (catalinadirect #F8002 $77 USD)
-Hose clamps (gears on outside of strap) 4 pairs (catalinadirect #Z1871 $23 USD per pair)
-Centek 1200214 1.62" x 45 degree fiberglass elbow (inet marine for $55 USD)
-Heat gun
-Lubricant (I used silicone)
-Hose removal hook

Steps:

1. Measure to make sure that the new hump hoses + the elbow will fit.  You don't want to be in a situation where you remove the old hose only to realize that you have the wrong length of new hoses!

2. Remove the old hose.  This is the most difficult part of the installation.  The old hose was a bear to remove because after 25 years on my boat it was hard as a brick and was solidly stuck on both ends especially the exhaust riser end - in fact the hose clamps were redundant to be honest!  It is not possible to remove the hose without cutting first, so I used an oscillating multitool to cut a section from the middle to allow enough slack to pull.  Be careful not to cut into the muffler fitting or the exhaust riser fitting!  After cutting, I used a silicon lubricant, heat gun, and a hose removal hook to remove both pieces of the hose.  It was a struggle, but the feeling of satisfaction when the hoses finally budged and spun off was immense!!

3. Clean the fittings and inspect them for any damage (especially the muffler inlet).  Muffler inlet fitting is approx 2.75" long (measured from the top) and exhaust riser fitting is approx 2.5".  In my case, there was no apparent damage to either fitting.  If you do have damage, you'll need to make the needed repairs/replacement before continuing.

4. Double-check your new hoses + elbow setup and then trim the new hoses to size.  I bought an 8" and a 6" just in case, but as it turns out two 6" would have been fine.

5. Apply lubricant to the fittings and inside of the hoses and muscle them in!  I put in the top one first (into the exhaust riser).   Be careful not to break the muffler inlet fitting.  Tighten up the clamps, but not too tight on the muffler inlet or elbow.

6. Run the engine to check for leaks, and adjust any clamps as needed.

7. Admire your work and enjoy the quieter/smoother ride!

[rmjohns]

Thanks for the write up! Something I'll be looking at doing soon, so the part numbers are a big help.

Rob

[Dave Spencer]

Nice write-up Andy.  I did this job on my Mk1.5 with a Universal M35AC engine about 11 years ago.  The configuration is slightly different.  I wrote it up here:
https://c34.org/bbs/index.php/topic,6878.msg45884.html#msg45884

You're right that getting the old hose off is the hardest part and cutting is the best way; maybe the only way.

[KeelsonGraham]

Great write-up, thank you! What's the thickness of the fibreglass elbow?

[AndyBC]

Thanks for the write up! Something I'll be looking at doing soon, so the part numbers are a big help.

Rob

The off season is the best time to do it!  Fyi I hard a hard time finding the elbow in stock, it took about 3 weeks to arrive in my case, so plan accordingly.  Let me know how it goes.

Fyi I probably should have completely removed the insulation to inspect the riser, especially after reading the other thread, but the insulation was stuck on good so it would have been a job to remove that and also to buy replacement insulation.  The riser felt solid from my casual inspection, and I haven't observed any leaks or fumes even with the old hose.

[AndyBC]

Nice write-up Andy.  I did this job on my Mk1.5 with a Universal M35AC engine about 11 years ago.  The configuration is slightly different.  I wrote it up here:
https://c34.org/bbs/index.php/topic,6878.msg45884.html#msg45884

You're right that getting the old hose off is the hardest part and cutting is the best way; maybe the only way.

Yours was a great write-up!  How has the hose held up after 11 years and did you end up changing the hose that goes into the nipple?

Also, the hump in your hose looks fatter than mine.  I wonder if they changed the design?  Yours looks like it could dampen more vibration.

[AndyBC]

Great write-up, thank you! What's the thickness of the fibreglass elbow?

It's a little less than 1/8 of an inch maybe?  Not as thick as the muffler inlet fitting, but it felt solid.

[Dave Spencer]

Nice write-up Andy.  I did this job on my Mk1.5 with a Universal M35AC engine about 11 years ago.  The configuration is slightly different.  I wrote it up here:
https://c34.org/bbs/index.php/topic,6878.msg45884.html#msg45884

You're right that getting the old hose off is the hardest part and cutting is the best way; maybe the only way.

Yours was a great write-up!  How has the hose held up after 11 years and did you end up changing the hose that goes into the nipple?

Also, the hump in your hose looks fatter than mine.  I wonder if they changed the design?  Yours looks like it could dampen more vibration.

My hump hose still looks brand new.  I'm in the process of replacing my transmission now and had to remove my engine to do so.  I'll be changing the hose that goes to the nipple as part of that job.  Getting the exhaust flange off the engine wasn't easy but it seems I had an easier job than some have reported.  The exhaust riser is still connected to the hump hose making it tricky to remove it from the exhaust flange studs.

I think the hump hose diameter is the same.  Mine is shorter so maybe it looks like it's smaller diameter because of that.  The two sizes (6" and 8") look to be different diameters on the Catalina Direct website but they are the same 1 5/8" ID.  https://www.catalinadirect.com/index.cfm?fuseaction=page.searchResults

[Ron Hill]

Andy : Nice installation. I believe that you only would have really needed one hump hose, but 2 is outstanding protection.

A thought